Yes, you can. Chickens can and will eat ANYTHING. I like mixing milk, raw eggs(no shell), and cooked grease or oil, corn oil and canned veggies in with my Broiler complete for my show chickens. They love it and always go crazy over it. With our laying hens and other chickens, we throw leftovers in there all the time, including meat, cooked veggies, old cerel and bread. Rotted fruit. They love it, and everytime we go out there they are running up and down the pen looking for more.
Hope I helped!